It’s official: [Engineer Bo] wins the internet with a video titled “Finding NEMA 17,” wherein he builds a dynamometer to find the best stepper motor in the popular NEMA 17 frame size.

Like a lot of subjective questions, the only correct answer to which stepper is best is, “It depends,” and [Bo] certainly has that in mind while gathering the data needed to construct torque-speed curves for five samples of NEMA 17 motors using his homebrew dyno. The dyno itself is pretty cool, with a bicycle disc brake to provide drag, a load cell to measure braking force, and an optical encoder to measure the rotation of the motor under test. The selected motors represent a cross-section of what’s commonly available today, some of which appear in big-name 3D printers and other common applications.

[Bo] tested each motor with two different drivers: the TMC2209 silent driver to start with, and because he released the Magic Smoke from those, the higher current TB6600 module. The difference between the two drivers was striking, with lower torque and top speeds for the same settings on each motor using the TB6600, as well as more variability in the data. Motors did better across the board with the TBC6600 at 24 volts, showing improved torque at higher speeds, and slightly higher top speeds. He also tested the effect of microstepping on torque using the TBC6600 and found that using full steps resulted in higher torque across a greater speed range.

At the end of the day, it seems as if these tests say more about the driver than they do about any of the motors tested. Perhaps the lesson here is to match the motor to the driver in light of what the application will be. Regardless, it’s a nice piece of work, and we really appreciate the dyno design to boot — reminds us of a scaled-down version of the one [Jeremey Fielding] demonstrated a few years back.

youtube.com/embed/MNTuMiNC2TU?…

The Parkside range of tools as sold in European Lidl stores may be reasonably priced, but it contains some products of far better quality than their modest cost would suggest. This means that Parkside hacking has become as much of a cottage industry as IKEA hacking, and they’re a firm favorite for modifications. [Gabriel-LG] has taken a Parkside robot mower, and converted it from a relatively mundane device to a fully-connected smart robot, with the aid of an ESP32.

The hardware is surprisingly simple, as all that’s really needed is a stop/go command. This can be readily found by hooking up to the input from the mower’s rain sensor, allowing the ESP to control its operation. Then there’s an accelerometer to allow it to count motion, and a hookup tot he battery to measure voltage. The firmware uses ESPHome, resulting in a mower now connected to home automation.

This isn’t the first time we’ve shown you someone upgrading the smarts on robot mover, and of course we’ve also taken a tour through the history of lawn mowers in general.

Cisco sta risolvendo una vulnerabilità di command injection zero-day in NX-OS. Ad aprile, questo bug è stato sfruttato dal gruppo di hacker di spionaggio informatico legato alla Cina Velvet Ant, installando malware con diritti di root sugli switch vulnerabili.

La vulnerabilità è stata identificata come CVE-2024-20399 colpisce l’interfaccia della riga di comando di NX-OS, consentendo a un utente malintenzionato locale di eseguire comandi arbitrari con diritti di root.

“Questa vulnerabilità è dovuta alla convalida errata degli argomenti passati a determinati comandi di configurazione della CLI. Un utente malintenzionato potrebbe sfruttare la vulnerabilità utilizzando i dati modificati come argomento per un comando CLI vulnerabile“, ha affermato Cisco.

Si sottolinea che per sfruttare con successo questo bug, l’aggressore dovrà prima autenticarsi come amministratore sul dispositivo vulnerabile. Il CVE-2024-20399 interessa gli switch Cisco MDS 9000, Nexus 3000, Nexus 5500, Nexus 5600, Nexus 6000, Nexus 7000 e Nexus 9000. Versioni firmware aggiornate sono attualmente disponibili per tutti i dispositivi.

Il rapporto dell’azienda rileva inoltre che Cisco è a conoscenza dello sfruttamento di questo problema nell’aprile 2024. Inizialmente la vulnerabilità e i relativi attacchi sono stati scoperti dagli specialisti della società di sicurezza informatica Sygnia, i quali sottolineano che questa attività era collegata allo spionaggio informatico e al gruppo di hacker cinese Velvet Ant.

Ricordiamo che il mese scorso i ricercatori di Sygnia avevano avvertito che Velvet Ant installava da molti anni malware personalizzati sui dispositivi F5 BIG-IP per ottenere un accesso costante alla rete interna dell’azienda presa di mira e rubare dati.

Come è ormai noto, il gruppo di hacker ha utilizzato un bug di Cisco NX-OS per lanciare malware precedentemente sconosciuti su dispositivi vulnerabili, connettersi ad essi da remoto, scaricare file aggiuntivi ed eseguire codice.

“Dato che la maggior parte degli switch Nexus non hanno accesso diretto a Internet, per sfruttare questa vulnerabilità, gli hacker devono prima ottenere l’accesso alla rete interna di un’organizzazione. Di conseguenza, il rischio complessivo per le organizzazioni è ridotto a causa delle difficoltà legate all’ottenimento dell’accesso necessario”, scrivono i ricercatori di Sygnia.

Tuttavia, l’azienda ha anche osservato che, nonostante le difficoltà nello sfruttare vulnerabilità come CVE-2024-20399, gruppi come Velvet Ant utilizzano solitamente dispositivi di rete scarsamente protetti per garantire un accesso costante agli ambienti aziendali.

L'articolo Cisco Risolve Vulnerabilità 0Day in NX-OS. Gli Hacker Cinesi di Velvet Ant la sfruttavano da Aprile proviene da il blog della sicurezza informatica.

Eccoci qui. Dopo aver trascorso gli ultimi anni leggendo tra il fediverso e il web alternativo, ho deciso di creare il mio posto dove le persone orientate alla libertà possano discutere di libertà nell'informatica e nella società. Lo scopo generale è ricreare le vibrazioni familiari dell'era BBS mettendo insieme strumenti vecchi e moderni, da IRC a Mastodon. Ecco dove spiego tutto:

- [ENG] dmi.unict.it/nfarceri/articles…
- [ITA] dmi.unict.it/nfarceri/articles…

Benvenuti a casa... vostra!

Questo è il primo articolo di questo sito, dove vengono introdotti gli scopi del sito stesso. In sintesi, il sito ha lo scopo di ricreare il feeling familiare e comunitario delle BBS degli anni '80 e '90 aggregando insieme più strumenti, vecchi e mod…

^{www.dmi.unict.it}

Throughout history, clean and potable water has been one of the most prized possessions, without which no human civilization could have ever sustained itself. Not only is water crucial for drinking and food preparation, but also for agriculture, cleaning and the production of countless materials, chemicals and much more. And this isn’t a modern problem: good water supplies and the most successful ancient cultures go hand in hand.

For instance, the retention and management of fresh water in reservoirs played a major role in the Khmer Empire, with many of its reservoirs (baray) surviving to today. Similarly, the Anuradhapure Kingdom in Ceylon (now Sri Lanka) featured massive reservoirs like Kala Wewa that was constructed in 460 CE with a capacity of 123 million m3. In the New World, the Maya civilization similarly created reservoirs with intricate canals to capture rainwater before the dry season started, as due to the karst landscape wells were not possible.

Keeping this water fresh and free from contaminants and pollution was a major problem for especially the Maya, with a recent perspective by Lisa J. Lucera in PNAS Anthropology suggesting that they used an approach similar to modern day constructed wetlands to keep disease and illness at bay, while earlier discoveries also suggest the use of filtration including the use of zeolite.

Resource Management

In climates where rainfall is plentiful, and where wells can fill in gaps, extensive water management is not a major concern. This is where the civilizations of Mesoamerica provide good illustrations of the effects this can have on societies, with the Aztec and Inca using aqueducts to bring mountain spring water to their cities, while the Maya in their region with a karst topography had to capture every drop of rainwater before it would vanish within the hollowed-out structures that are a distinctive feature of these soluble carbonate rock landscapes.

This meant that the only time when the Maya could refill their reservoirs was when it rained, which also placed significant restrictions on how much water would be available to any population. It is postulated that it was a drought and reservoir pollution led to the eventual abandonment of the Mayan city of Tikal (ti ak’al in Yucatac Maya, but Yax Mutal (‘First Mutal’) according to inscriptions within the city) after the Late Classic Period (~900 CE). This preceded the Terminal Classic period, during which much of the lowlands were abandoned.

There is strong palaeoclimatological evidence for a sustained drought between 800 – 1000 CE (likely related to the Medieval Warm Period) in and around the Yucatán Peninsula, coinciding when archeological evidence shows a reduced human presence in these lowlands by the Maya. It’s thought that these droughts coincided with epidemic diseases in combination with dense populations and intensification of agriculture with associated ecological destruction. The post-classical Maya period featured far less dense cities, and despite the often used term of ‘Classic Maya Collapse’, Mayan society was only regionally affected and persists to this day, despite efforts by European invaders and associated occupation over the centuries.

Filtration

Hypothetical scheme of the ancient water purification system at Tikal. Macro-crystalline quartz crystal sand and zeolite filtration system positioned just upstream of, or within the reservoir ingress. (Credit: Kenneth Barnett Tankersley et al, 2020, Scientific Reports)
Water filtration is something that happens not just with man-made structures and mechanisms, as anyone who uses water from springs and wells uses knows. The granular structure of soil serves to filter out larger and smaller contaminants as well as bacteria and other potential disease carriers. This same principle can be applied with artificial water filtration systems, with the Corriental water reservoir at the city of Tikal providing evidence that the Mayans even used the zeolite mineral for its water purification properties.

This was discovered by Kenneth Barnett Tankersley and colleagues, and published in 2020 in the journal Scientific Reports. They discovered that the water in this reservoir was filtered through a mixture of zeolite and coarse crystalline quartz. Zeolite is interesting, as it has adsorbent and ion-exchange properties which make it a popular choice even today for water purification to the point where most zeolite is synthesized for this and other purposes.

As for whether this extensive filtration in Mayan reservoirs was common is unknown, as the authors succinctly point out that the number of excavations of these reservoirs is quite limited. The presence of zeolite would have significantly helped with filtering out contamination from microbial sources like cyanobacteria and toxins such as cinnabar. The latter is both a historically common brilliant red pigment as well as a good source of toxic mercury due to its mercury sulfide composition. Unfortunately this kind of filter does not help against mercury from volcanic sources due to its very small particle size, meaning that this type of contamination would have built up over the years in reservoirs.

Circle Of Life

LiDAR map of Tikal highlighting some of its reservoirs. LiDAR-derived hillshade image created by Francisco Estrada-Belli of the PAQUNAM LiDAR Initiative with additions by Christopher Carr and Nicholas Dunning.
The term ‘constructed wetland‘ pretty much gives away the concept: these create an artificial wetland ecosystem where plant and often also animal life work to treat sewage, greywater, stormwater runoff, and wastewater in general. They provide both a filtration function and a remediation one, with the vegetation along with microbial life serving to break down and process excess elements, while maintaining a healthy pH and nutrient levels.

In the mostly stagnant water reservoirs which the Maya maintained, preventing the build-up of organisms and harmful pollutants was essential, leading to likely extensive use of aquatic plants in these reservoirs. This is reflected in the headdresses, architecture and other elements of Mayan culture where the clean water-loving water lily (nymphaea ampla) is prominently displayed and associated with prosperity and the leadership.

Likely many different aquatic plants were used in combination with water lilies, along with various types of fish. This would have helped to deal with pests like mosquitoes and their aquatic offspring, reduce evaporation and creating a self-sustaining cycle where the waste from the fish would have provided nutrients for the plants, who themselves would have provided shade and food for these fish. Settlement maps show that the Maya did not generally build residences near the reservoirs, likely keeping human waste run-off to a minimum.

This healthy system did however begin to break down during the Late and Terminal Classic period, with the sediment record showing a gradual increase in contamination from cyanobacteria and human waste. This gives a sobering insight into the final years of the city of Tikal and areas like it that got hit worst by the drought.

Lessons For Today

Although we often like to regard droughts and access to potable water as historical problems, even today one in four humans does not have access to safe drinking water, with unsafe water being responsible for about a million deaths each year. Unsafe water can include water that is contaminated with infectious diseases such as cholera, with much of Africa and Asian countries like India heavily affected in this manner, but even wealthy countries like the US seeing its share of drinking water contamination incidents, with that of Flint, Michigan, being just one of many.

Such forms of contamination and lack of access to safe drinking water are obviously issues that ought to be resolved and prevented as well as possible once the cause has been determined. These days we don’t necessarily have to rely on constructed wetlands courtesy of modern technology, but they could be very beneficial as a self-sustaining water purification system.

As the US Geological Survey (USGS) points out, we are dealing with increasing drought since 2000 as well. This doesn’t merely translate into less rain, but also the rain and melting patterns, not to mention the availability of groundwater. This becomes apparent in periods of extreme drought interrupted by extreme rain accompanied with floods. As this makes water availability less predictable for drinking water and agriculture, the creation of reservoirs may be advisable, both to reduce the impact of floods and as buffers for dry periods.

Today we have many reservoirs that were formed due to dams blocking the course of rivers, but something similar could be done for rainwater, not unlike historical cisterns that once used to be extensively used throughout the world, like the famous Basilica Cistern below the city of Istanbul. It’s perhaps ironic that many of such cisterns were abandoned over the years, even as the need for them becomes more apparent today.

How do you talk USB Power Delivery (PD)? Grab a PHY? Use a MCU with one built-in? Well, if you’re hardcore enough, you can do it with just a few resistors and GPIOs. [eeucalyptus] shows you their implementation of USB-PD on a CH32V003, which has no PD peripheral, building a PD trigger, everything is open source, and they walk you through the entire thing including low-level PD basics, too!

It helps that CH32V003 is a 32-bit MCU with a good few resources and peripherals, for instance, an internal comparator. Other than that, you don’t need much in terms of hardware resources, but you do need a steady hand — parts of the firmware had to be written in assembly to keep up with PD timing. Want to tinker with the fruit of this research, perhaps, further build upon the code? There’s an example board on GitHub, too!

Want to try your own luck with this method? There’s a schematic, and logic analyzer captures, and a board to refer to. Again, more than enough information on every single low-level detail! Otherwise, grab an MCU pre-programmed to talk PD, maybe a trigger board chip, or maybe even a PD PHY and implement PD communications with it directly – it’s pretty easy!

We thank [Julianna] for sharing this with us!

At the request of Pirate Party MEP Patrick Breyer, EU Internal Market Commissioner Breton has commented on manufacturers who equip their products with “kill switches”. This question was prompted by a recent case in which the Polish train manufacturer NewAg was found to have installed “kill switches” in several electric multiple units, which switch off the train’s power supply and compressors under certain conditions (location or operating time). Among other things, the manufacturer implemented the switch-off function to prevent the trains from being repaired by competitors and also to prevent the train software from being analysed. In his response, EU Commissioner Breton admits that existing or planned EU rules on the right to repair are largely limited to the protection of consumers and do not apply to businesses.

Patrick Breyer comments:

“The practice by some manufacturers to prevent independent companies from repairing and servicing products is unacceptable. The EU should put clear rules in place to prevent such abuses and protect the rights of users, as well as the competitiveness of independent repair services. The right to repair should also apply to business customers.

However, a mere right to repair falls short of what is needed in the digital era. Users must be given full control over the technology they use in their daily lives. We need a right to modify, customise and improve our legally acquired devices. The fact that copyright law currently prohibits this is disempowering and invites abuse, as the Polish case shows.”

A similar problem is also observed with computer games, where manufacturers make popular games unusable at will. In collaboration with the gamer initiative “Stop killing games”, the pirate party is calling for cultural protection of video games.

patrick-breyer.de/en/stopkilli…